This is easily reproduced on a BBB by enabling the peripheral port only(as the host port may enable the shared clock) and keeping itdisconnected so that the controller is runtime suspended. (Well, youwould also need to the not-yet-merged am33xx-suspend patches by DaveGerlach to be able to suspend the BBB.)

This is a regression that was introduced by commit 1c4d0b4e1806 ("usb:musb: Remove pm_runtime_set_irq_safe") which allowed the parent gluedevice to runtime suspend and thereby exposed a couple of older issues:

Register accesses without explicitly making sure the controller isruntime resumed during suspend was first introduced by commit c338412b5ded("usb: musb: unconditionally save and restore the context on suspend")in 3.14.

Commit a1fc1920aaaa ("usb: musb: core: make sure musb is in RPM_ACTIVE onresume") later started setting the RPM status to active during resume,and this was also implicitly relying on the parent always being active.Since commit 71723f95463d ("PM / runtime: print error when activating achild to unactive parent") this now also results in the followingwarning: